The perfect match: making breast cancer treatment more personal

In the build up to this year’s Stand Up To Cancer, we’re running a series of posts that focus on the science that is happening around the country thanks to your generous donations and amazing fundraising. The fifth and final post in our series focuses on finding faulty genes to improve breast cancer treatment.

Imagine you’re walking through a forest, teeming with a unique collection of life that’s unlike any other in the world.

You want to know more about what makes up this dense and diverse environment to find the best way to manage it, so you pick one spot and sample what’s there.

But can that one sample really paint a picture of the forest area as a whole, and highlight the variation that’s present throughout?

This is a situation that scientists and doctors in cancer medicine face. Tissue samples, or biopsies, only provide a snippet of what’s going on throughout the tumour.

Not knowing the full picture means that achieving truly personalised medicine – where each patient’s treatment is tailored to their cancer – seems like a faraway goal.

But scientists are now realising that blood, and the fragments of tumour DNA floating within it, could provide a much more accurate picture of a cancer’s complexity than biopsies.

By tapping into this resource, Stand Up To Cancer-funded scientist Dr Nick Turner is helping to change the way that patients with breast cancer are treated.

“Advances in technology mean we can now glean vast amounts of information from a simple blood test that we used to have to get from a tumour biopsy,” says Turner, from London’s Institute of Cancer Research.

“These ‘liquid biopsies’ enable us to track more accurately what’s going on in a tumour over time.”

Widening the net

Tumours are caused by faults in our DNA – the genetic ‘recipe book’ that contains the instructions to make our cells. When the recipe is flawed, cells can begin to grow uncontrollably, developing into a cancer.

It’s these mistakes that interest scientists chasing personalised medicine. That’s because treatments that target a tumour’s specific genetic weakness, rather than a ‘one-size-fits-all’ approach, could prove to be more effective in tackling that cancer. It’s like switching from using a general weed killer and only expecting to harm the troublesome plants to picking off certain weeds one by one.

The idea may sound simple enough, but putting it into practice is tricky.

We need a non-invasive test that can be repeated and done at the right time, when a patient needs treating

– Dr Nick Turner

As a tumour grows it also changes, developing more genetic flaws as time goes by. As a result, the genetic faults found in one part of a tumour could be vastly different from another. So the information gathered from biopsies could vary depending from where in the tumour each sample is taken from.

“We can’t repeatedly biopsy tumours,” says Turner. “Biopsies are invasive and painful, and for some advanced cancers the tumour isn’t accessible. We need a non-invasive test that can be repeated and done at the right time, when a patient needs treating. This will give us up-to-date information about what’s going on at the genetic level.”

And according to Turner and others working in the field, ‘liquid biopsies’ could be a solution that scientists have been seeking.

Unearthing a secret goldmine

Just as new cells are constantly being born inside a tumour, others are dying and shedding their contents into the blood like ashes to the wind. Importantly, this includes their DNA, giving scientists a unique opportunity to read the cancer’s secret genetic recipe.

“We know that there are lots of different faulty genes in a tumour that can drive breast cancers to grow,” Turner says. “We want to use liquid biopsies to identify them so we can match this genetic information with the right treatment.”

And that’s exactly what Turner and his team will be doing in his upcoming clinical trial, called plasmaMATCH, which is detailed in the video below:

• Check out YouTube for an animation describing the plasmaMATCH clinical trial

After enrolling 1,000 patients with advanced breast cancer, the team will take blood samples and scour the tumour DNA within them. People who have genetic flaws that could be targeted with drugs will then be given treatment tailored to their cancer.

“At the moment we’re looking at drugs that are in clinical development, so they’re not routinely available yet,” Turner says. “But this will be one of the studies that will enable them to get to patients on trials.”

Surfing towards success

Alongside opening up treatments to patients, gathering more information on the faulty genes involved in breast cancer during the trial could also lead to new targeted drugs.

“Although there are some common faulty genes in breast cancer, many are very rare and only found in one or two per cent of patients,” Turner explains. “Yet in those patients, these genes are probably the key to treating that particular cancer.”

And while breast cancer may be the focus of this study, Turner says that the technique could also be applied to other cancers.

“We’re aiming to show that, through a simple blood test, it’s easy to screen large numbers of patients and find those rare faulty genes. Then we’ll be able to work out how best to treat each patient.”

Ultimately, Turner hopes that his team’s work will lead to the biopsy needle being traded in for its much finer blood sampling counterpart.

And as part of the swap, a more personalised and precise way of treating people with cancer could be on the horizon.

Justine